Question

number 2 sketch please

Relevant i = 12 nuclei and relative natural abundances are as follows (assume all other nuclei are spin inactive): 19F (1 = /2, 100%) TH (1 = 12, 100%) 295i (1 = 42, 4.7%) 31P (1 = /2, 100%) 77 Se (1 = 12, 7.6%) Also, assume 1 > 2/> 34, there is no resolvable 4 coupling, and there is no observable coupling to 13C nuclei. 1. Using stick diagrams, sketch the TH NMR spectra for the following compounds. Assume structures are rigid in solution (give all isomers). Include all relative peak intensities and label all couplings. a) PBrzMe b) AsFMe2 c) SeMe2 d) PF Me e) SbCI(CH2CH3)2 2. Using stick diagrams, sketch the 31P NMR spectra for the following compounds. Assume structures are rigid in solution (give all isomers). Include all relative peak intensities and label all couplings. a) MezP-SiMe3 (1H decoupled) b) PF4CI c) H2P(CF3) d) PF5 e) P(CF3)3

Answer 1

Question 2.

a) Doublet (d) appears.

Explanation: Phosphorus couples with the adjacent ²⁹Si, and gives a signal with multiplicity = n + 1 = 1 + 1 = 2.

b) Quartet of doublet (qd) appears.

Explanation: Phosphorus first couples with 3 equatorial ¹⁹F, followed by the axial¹⁹F, and gives a signal, i.e. qd.

c) Quartet of triplet (qt) appears.

Explanation: Phosphorus first couples with 3 ¹⁹F, followed by 2 ¹H, and gives a signal, i.e. qt.

d) Sextet (at room temperature); quartet of triplet (at low temperature) appears.

Explanation: At room temperature, all the five F's undergo rapid exchange from axial to equatorial, whereas at a low temperature such as -78^oC,  phosphorus first couple with 3 equatorial ¹⁹F, followed by 2 axial ¹⁹F.

e) Dectet appears.

Explanation: Phosphorus couples with 9 ¹⁹F, and gives a signal with multiplicity = n + 1 = 9 + 1 = 10.